Systems are known that use a single communications bus to transmit communications signals between a control panel and remote peripheral devices. However, such systems can be rendered inoperable when a fault develops or is induced by deliberate interference or tampering on the communications bus wiring or on a bus interface of one of the peripheral devices. For example, on a four wire RS485 bus, connecting the A, B, power, or ground connections improperly will prevent a control panel from receiving communications signals indicative of polling events from peripheral devices as well as any other data signals transmitted between the control panel and peripheral devices connected to the bus.
Although a communications bus is a single unit, it is to be understood that internal communications bus cabling, as used herein, can include the portion of the bus cabling within a control panel enclosure, and that external communications bus cabling, as used herein, can include the portion of the bus cabling that extends outside of the control panel enclosure. A control panel can be connected to one or more of an Ethernet module, a GSM/GPRS module, a modem, or other communications device that can be used to report an alarm, fault, or status condition to a remote receiver, such as a reporting station. Typically, each of these communications devices is housed within the control panel enclosure and is connected to the control panel via the internal communications bus cabling. However, the control panel and the communications devices housed within the control panel enclosure can also be connected to peripheral devices, such as keypads and sensors, via external communications bus cabling. In known systems, any fault on or malicious tampering or interference with the external communications bus cabling or peripheral devices attached to the external communications bus cabling can render the entire communications bus, including the internal communications bus cabling, inoperable, thereby preventing the control panel from communicating alarms, faults, or status conditions to a remote receiver via one or more of the communications devices connected to the internal communications bus cabling.
FIG. 1 is a block diagram of system 100 that includes a communications bus as known in the art. As seen, the system 100 can include a control panel 110, and one or more communications devices 120 housed within a control panel enclosure 130 and connected to the control panel via internal communications bus cabling 140. Each of the control panel 110 and the communications devices 120 can also be connected to one or more peripheral devices 150 that are located outside of the control panel enclosure 130 via external communications bus cabling 160. As described above, communications between the control panel 110 and the communications devices 120 via the internal bus cabling 140 are vulnerable to faults on or tampering or interference with the external bus cabling 160 and the peripheral devices 150.
Some systems have been developed to overcome the susceptibility to faults on or tampering or interference with known communications buses. For example, some control panels include a communications device housed within the control panel enclosure and connected to a communications bus, as described above, as well as a dedicated communications device, such as a POTS telecommunications device or modem, connected directly to the control panel and not via the communications bus. Accordingly, when tampering occurs on the external cabling of the communications bus, thereby rendering communications between the control panel and the communications devices connected to the communications bus inoperable, the control panel can still communicate via the dedicated communications device.
Unfortunately, not all control panels include or can support a dedicated communications device, such as a modem. For example, some control panels do not have access to a land line telephone connection to operate with an onboard modem. Accordingly, such control panels remain susceptible to faults on or tampering or interference with a communications bus, and systems that include such control panels may become incapable of reporting alarm, fault, or status conditions, thereby making such systems incapable of protecting, monitoring, and controlling an associated monitored region in the manner expected by a user.
Other systems that have been developed to overcome the susceptibility to faults on or tampering or interference with known communications buses include control panels that include two separate communications buses: one communications bus for connecting the control panel to devices internal to the control panel enclosure and another communications bus for connecting the control panel to devices external to the control panel enclosure. Undesirably, such systems require additional control panel resources, such as a second microprocessor, UART, memory device, and the like, as well as software and other components to support a second bus interface.
In view of the above, there is a continuing, ongoing need for improved systems and methods.